Publications

Matrix stimulation of carbonate reservoirs, despite being a mature technique, still presents a challenge when long horizontal openhole completions are producing from fractured formations close to wateroilcontacts. Total zonal coverage of long carbonate sections, in particular when horizontal, remains a challenge. Uniform distribution of the stimulation fluid, while limiting entry into the natural fractures and possible water sources, requires careful selection of fluids, diversion and placement techniques. This case history describes a successful stimulation of a carbonate formation employing a viscoelastic surfactant based self-diverting acid fluid, placed through coiled tubing, using a rotary jetting tool, taking advantage of the existing Y-tool ESP completion. In this particular case, the logistical constraints that precluded the use of a workover rig also required particular attention to be given to the protection of the ESP pump system from the effects of the raw and spent acid. The stimulation treatment increased the production of the well from 200 bopd up to 500 bopd while saving the cost of a full workover operation in a remote location. The increased water production was an expected possibility, and is being handled within the capabilities of the artificial lift system and existing surface facilities.